A gunman opened fire in Sandy Hook Elementary School in Newtown, CT, killing 27 – 18 of which are children – before dying of a self-inflicted gunshot wound.

Residents of Newtown, CT, are memorializing the victims of the Sandy Hook Elementary shooting. A gunman opened fire at the school, killing 26 – including 20 children – before dying of a self-inflicted gunshot wound.

NEWTOWN, CT (RNN) - At least 28 people are dead, including 20 children, after a shooting at Sandy Hook Elementary School on Friday, according to a Connecticut State Police spokesman. Law enforcement officials are working through the night to identify bodies and notify families, and a spokesman said they will release the names of the victims in a news conference at 8 a.m. ET Saturday.

Police officials told the Associated Press that the suspected gunman is 20-year-old Adam Lanza. His mother, Nancy Lanza, who was a teacher at the school, was found shot dead at the home she shared with Adam Lanza. He left her there and drove to the school in her car.

Adam Lanza and six adults were among the dead at the scene.

An earlier report from law enforcement mistakenly mixed up the suspected shooter's name with his brother, 24-year-old Ryan Lanza. The brother was detained for questioning by police, according to the AP. Authorities do not believe he is an accomplice.

Ryan Lanza, who had not had contact with his younger brother since 2010, told law enforcement that Adam Lanza had a history of mental health problems.

It is the second deadliest school shooting in American history. The largest mass shooting at a school campus was at Virginia Tech University on April 26, 2007, when 32 people were killed and 17 more were injured. This is the second mass shooting this week after Jacob Roberts opened fire in a Portland, OR, mall, killing two and wounding one before committing suicide on Tuesday, Dec. 11.

President Barack Obama made an emotional address to the nation, pausing to brush tears from his eyes and compose himself.

"Our hearts are broken today for the parents and grandparents, sisters and brothers of these little children, and for the families of the adults who were lost," Obama said in a news conference. "May God bless the memory of the victims. And in the words of scripture, heal the brokenhearted and bind up their wounds."

Hundreds of community members and family members mourned the loss of lives at a vigil that was given hours after the massacre.

According to AP, the church was filled to capacity, hundreds spilled outside, some of them holding hands in circles and saying prayers. Others lit prayer candles and sang "Silent Night."

Connecticut State Police spokesman Lt. Paul Vance said at a Friday afternoon news conference that 18 children died at the scene of the shooting, and two more died after being transported to hospitals. Six adults and the gunman died at the scene, Vance said. Another adult victim who was transported to the hospital did survive.

Vance would not comment on the identity of the victim at the secondary location. He also said the identifying of victims will be a painstaking process, and that the families will be the first to be informed.

"We will leave no stone unturned as we look at every facet of this investigation - the shooter, victims - everything," Vance said.

Law enforcement officials said that the shooter killed himself with a self-inflicted gunshot.

Connecticut Gov. Dannel Malloy also spoke at the news conference. He said the person responsible for the shooting was dead, "as is an individual the perpetrator lived with." Vance said police secured a secondary crime scene where another adult was killed.

A CNN reporter said police recovered three weapons at the scene: a Glock and a Sig-Sauer, which are handguns, as well as a .223 Bushmaster rifle. The rifle was in the back seat of the car the gunman drove to the school, the handguns were inside the school. The car belonged to Nancy Lanza.

Security measures implemented this year at Sandy Hook kept doors locked during class hours, and people have to be buzzed in before entering. There is a camera to view whoever enters the building.

After the shooting began, someone may have activated the loudspeaker system as a way of warning others in the school. A scream was heard over the speakers.

A parent who was at the school told a CNN producer that the principal, vice principal and school psychologist left the office right after shots rang out. The vice principal, who had been shot in the foot or leg, crawled back into the office.

The parent said she saw the other two lying in the hall, along with children, "in pools of blood," according to the producer.

Authorities said the suspected gunman's body was in a kindergarten classroom. At least some of the shooting took place inside that room.

According to WFSB, authorities received word of the incident at the school around 9:41 a.m. ET.

Reporters on the scene observed a man in camouflage gear being taken away from the staging area. He screamed to people that he was not involved in the shooting.

When police from state and local agencies arrived on scene, they began a search of the building, going room to room. Students and faculty were evacuated to the nearby Sandy Hook Volunteer Fire Department.

Danbury Hospital had at least three people admitted as a result of the incident, including a teacher who got shot in the foot, CNN stated. WFSB said officials at Bridgeport Hospital confirmed that they had admitted one woman who was shot, and she was in stable condition.

The school superintendent's office announced all campuses in the district had been locked down, and kindergarten classes at the school were canceled.

President Barack Obama held a news conference at 3:15 p.m., saying he ordered for all flags across the country to fly at half-staff. In an emotion-filled statement, he said he felt the pain of the tragedy as a parent, not a president.

"We're going to have to take more action to prevent tragedies like this, regardless of the politics," Obama said.

The Newtown Public school system operates seven schools. There are four elementary schools, including Sandy Hook, that serve grades K to four, one intermediate school serving grades five to six, one middle school serving grades seven to eight and Newtown High School serving grades nine to 12.

Newtown is a town of nearly 28,000 located in Fairfield County, CT, about 48 miles southwest of Hartford. Sandy Hook Elementary has a student enrollment of 672, according to the Connecticut State Board of Education website.

A gunman opened fire in Sandy Hook Elementary School in Newtown, CT, killing 27 – 18 of which are children – before dying of a self-inflicted gunshot wound.

Residents of Newtown, CT, are memorializing the victims of the Sandy Hook Elementary shooting. A gunman opened fire at the school, killing 26 – including 20 children – before dying of a self-inflicted gunshot wound.